Extraction of lumped structural parameters from multiphysics field simulations for MEMS switches

This paper investigates the extraction of lumped parameters (elastic coefficient and effective mass) for RF MEMS switches. The extraction starts from field simulations obtained with the finite element method, which solves strongly coupled structural-electrostatic field problems, and is based on least square fitting. The elastic coefficients are extracted from static coupled simulations, whereas the effective mass is extracted from a dynamic, without damping, unforced, transient simulation. The degree of system nonlinearity can be estimated from the static simulation. If the system is close to linearity with respect to its structural behavior, then a simple algorithm to extract the effective mass is proposed. The validations are carried out by comparing the initial field results with the results obtained from the reduced order models. Relative errors less than 8 % are obtained for the pull-in voltage for all the structures investigated.